Figure REF  (Top) shows the time series of the Borexino rate in the RoI in time bins of 30 days. The figure clearly shows secular trends in \(R(t)\) , which could bias the measured amplitude of periodic modulations [1]}. A detrending procedure is thus carried out by subtracting an empirical
combination of exponential trends:
\(R(t) = R_A e^{-t/\tau _A} + R_B e^{-t/\tau _B} \approx R_A e^{-t/\tau _A} +R_B\left(1 - \frac{t}{\tau _B}\right),\) 
